Flasher



y 1949- H. R. GROSS 2,477,408

FLASHER Filed Aug. 30, 1946 2 Sheets-Sheet 1 INVENTOR.

1591a Z. 6705;? 55 BY J 20 Arrrsr Patented July 28,1949

UNITED STATES PATENT OFFICE 2,477,408 msnaa Henry R. Gross, Chicago,Ill. Application August so, 1946, Serial No. 694,117

(crane-113) 1 Claim. 1

This invention relates to flashers, and particularly to thermalflashers.

An object of this invention is to provide an improved thermal flasherhaving a rapid and positive switching action and which is particularlywell adapted to be used, for example, in vehicle turn signal systems.

Another object is to provide an inexpensive flasher having a bimetallicmember so constituted that it may oscillate rapidly and yet is capableof satisfactorily operating 'the movable switch parts associatedtherewith. I have found that by so forming the bimetallic member that ithas a highly flexible working 'portion and a relatively still free endportion, th member is instantly responsive to variations in electriccurrent of small magnitude flowing through it for opening or closing theswitch contacts with relatively small movement of the working portion.The stiif end portion of the member amplifies the motion of the workingportion and imparts suflicient rigidity and leverage to the free end ofthe member to operate the switch in the desired manner, making andbreaking an electrical circuit to the signal lights or other indicatorsat a rate of from 60 to 120 times per minute and yet effecting deflniteclosure of the circuit each time so that the lights come to fullbrilliance before the circuit is interrupted.

Further objects of the invention are to eliminate the necessity forprecise balancing of spring pressures in a thermal flasher and to.equalize the on-time and off-time of the flasher. These features arerealized by aconstruction in which the bimetallic strip is mounted inofiset relation to a switch contact blade to which it is connected by atoggle or the like, and wherein the bimetallic member is worked betweentemperature limits which are considerably higher than the ambienttemperature so that the heat dissipation is always at a relatively highrate while the flasher is in operation.

Various other objects, advantages and features of the invention will beapparent from the following speciflcation when taken in connection withthe accompanying drawings wherein a certain preferred embodiment is setforth for purposes of illustration.

In the drawings, wherein like referenc 11 merals refer to like partsthroughout:

Fig. 1 is a perspective view of a flasher con- Fig.2 is a sectional.view through the housing taken on the line 2-2 in F18. 1 and showing theflasher in plan;

Fig. 3 is a sectional view through the housing on the line 3-3 in Fig. 1and showing the flasher in end elevation;

Fig. 4 is a fragmentary sectional view taken on the line 4-4 in Fig. 2;

Fig. 5 is a disassembled detail view of a portion of the flasher;

Fig. 6 is a longitudinal section taken on the line 66 of Fig. 2 andshowing the positions of the parts when the flasher is not operating;

Fig. 7 is a sectional view similar to Fig. 6 but showing the parts incertain relative positions which they may occupy when the flasher isoperating; v

Fig. 8 is a view similar to Fig. 7 but showing the flasher parts instill other operative positions; and

Fig. 9 is a schematic diagram of a vehicle turn signal circuit in whichthe flasher may be connected.

Referring now to the drawings, and particularly to Figs. 1 through 4thereof, the flasher is mounted on an insulating base or plate l0 and iscovered by a suitable metal housing I! to which is attached a bracket Hfor mounting the flasher in its position of use. A block ii of insulatinmaterial is secured to the base I0 and serves as a support for a springcontact blade or yoke l8 and a bimetallic strip or member 20, theseparts being shown in detail in Fig. 5. The blade IB'has a tail portion22 which is secured to the top of the block IS. A central channel orrecess 2|, Fig. 4, is provided in the block l6, and one end of thebimetallic mem ber 20 is disposed in said channel and anchored to theblock it by rivets 50. To insure a good electrical connection betweenthe bimetallic strip 20 and the contact bladeil, a pigtall 26 ofsuitable conducting material such as copper foil extends between and issoldered or otherwise suitably secured to the tail portion 22 and thebimetallic strip 20. It will be noted that the fixed ends of the contactblade I! and the bimetallic member 20 are disposed in planes which aresubstantially ofl'set with respect to each other, the purpose of thisconstruction being explained presently.

The bimetallic member 20, as shown more clearly in Fig. 5, has a narrow,highly flexible working portion 28 intermediate its flxed end and thefree end thereof. This enables the strip 20 to respond rapidly tochanges in temperature such as may be produced by variations in anelectric current of small magnitude flowing through the member 2|. Thefree end of the member 28 is still, such stiflening preferably beingaccomplished by securing a small rigid piece 38 to the free end of themember 28.

The contact blade I8 is formed with a longitudinal opening 32, thereinso that it resembles a yoke. The blade l8 and member 28 extend ingenerally the same direction from the block IS, the member 28terminating short of the far end of the opening 32. An arched spring 34having cuplike indentations or sockets 36 at its ends is disposedbetween the blade l8 and the member 28, the spring 34 arching upwardlythrough the opening 32 in the blade l8 and its cupped ends 36respectively engaging the free end of the member 28 and an abutment 35on the blade 18,

' Near its free end the contact blade l8 carries two contacts 38 and 48,Figs. 3 and 5, on opposite faces thereof, these contacts respectivelycooperating with fixed contacts 42 and 44. The fixed contact 42 ispositioned above the blade i8 and is carried by a bracket 48 which isattached to the insulating base 18. A terminal 48 is. mounted on theexterior of the base l8 and is electrically connected to the bracket 46as by rivets 58 which pass through the bracket 46 and terminal 48. Thefixed contact 44 is carried by a bracket 52 mounted on the base I, thebracket 52 being connected as by rivets 54 to a terminal 55 on theexterior of the base III. A terminal 58, Fig. 4, on the base I8 iselectrically connected to the means such as rivets 68 which extendthrough the base It! and block iii.

A wiring diagram which illustrates the flasher in association with atypical vehicle turn signal switch 88. One pole 18 of the switch 88 iselec-- trically connected in parallel to the left rear and left frontturn signal lights 12 and I4, respectively. The other pole 16 of theswitch 88 is electrically connected in parallel to the right rear andthe right front turn signal lights 18 and 88, respectively. The turnsignal lights 14 and 88 are mounted on the front of the vehicle to theleft and right, respectively, of the operator, while the turn signallights I2 and 18 are mounted on the rear of the vehicle to the left andright, respectively, of the operator. All of the turn signal lights 12,14, 18 and 88 are grounded on the sides thereof opposite those which arein electrical connection with the switch poles 18 and 18.

The positions occupied by the various parts of the flasher when the sameis in a non-operating condition are illustrated in Fig. 6. The spring 34normally urges the contact blade l8 upwardly so that .the' contact 38carried thereby bears against the stationary contact 42. Likewise, whenthe bimetallic strip 28 is at ambient temperature, the spring 34 urgesthe bimetallic strip 28 downwardly, this motion being limited by a stop82 fixed in the base 18 to prevent the member 28 from acquiring apermanent set.

When the operator of the vehicle desires to signal a turn, say to theleft, he moves the arm 68 of the selector switch 88, Fig. 9, until itengages the pole 18 of this switch. This establishes a circuit from thebattery 52 through the bimetallic member 28, blade 18, and switch 68 tothe fixed end of the bimetallic member 28 by suitable '4 turn signallights 12 and I4. As the current flows through the member 28, thismember is heated and curls upwardly, passing through the position shownin Fig. 7 and into the position shown in Fig. 8. The action of thespring 34 is such that as the still end 38 of the member 28 approachesthe blade I8, the blade I8 is toggled and snaps sharply downwardly toseparate the contacts 38 and 42 and bring the contacts 48 and 44 intoengagement as shown in Fig. 8. Such action breaks the circuit to theturn signal lights I2 and 14 and establishes a circuit through the pilotlight 64. The current drawn by the pilot light is insuflicient tomaintain the member 28 heated to the extent necessary for remaining inthe position shown in Fig. 8. Hence the member 28 cools and commences tostraighten, When it assumes the position shown in Fig. 7, the contactblade I8 is again toggled by the spring 34 to separate the contacts 48and 44 and engage the contacts 38 and 42. Assuming that the selectorswitch 68 is still closed as described, current again passes through thebimetallic strip 28 and blade 18 to the signal lights 12 and 14 untilthe member becomes sufllciently heated to assume theposition shown inFig. 8 whereupon the above described cycle of operations is repeated.The flasher thus functions alternately to make and break the circuits tothe turn signal lights and the pilot light, causing these lights toflash at the rate of from 60 to 120 times per minute.

It should be noted that the bimetallic member 28 never assumes theinoperative or cold" position thereof shown in Fig. 6 so long as theselector switch 68 is closed. That is to say, the member 28 oscillatesbetween the positions illustrated in Figs. 7 and 8 without coming torest against the stop 82, while the signal lights are being flashed.When the switch 88 is opened, the member 28 then cools and straightensuntil it is arrested by the member 82.

When the right turn signal lights 18 and 88 are to be flashed, theoperator moves the switch 68 to bring the arm 66 thereof into engagementwith the pole l6, whereupon the above described operations are repeatedexcept that the signal lights 18 and 88 and the pilot light 64 areflashed.

Numerous outstanding advantages are afl'orded by the invention hereindisclosed. The particular form of bimetallic strip 28, Fig. 5, which isemployed has been found to give highly satisfactory performance invehicle turn signal systems where the current flowing in the circuit isapt to be of relatively small magnitude. The narrow, highly flexibleworking portion 28 of the member 28 enables it to respond rapidly tovariations in a current flowing through it so that the member 28 is ableto oscillate quite rapidly. The stiff end portion 38 of the member 28amplifies the motion of the working portion 28 and imparts suificientrigidity to the free end of member 28 for satisfactory coaction with thearched spring 34. The toggle action of the member 28 on the blade l8through the medium of the spring 34 produces a positive snap motion ofthe blade [8 for making and breaking the associated electrical circuits.There is no fluttering of the contacts and hence a minimum of sparking.Resort may be hadtto conventional expedients for further reducingcontact sparking, if desired, such as by making the movable andstationary contacts of different materials, a satisfactory combinationfor this purpose being tungsten and silver.

Still another advantage is the ease of adjustment of the flasher whichis realized by mounting the member 20 and the yoke or blade [8 indifferent planes so that they are transversely offset from each other.This feature has been found to reduce materially the amount of timerequired for adjustment of spring pressures and the number of factoryrejects. Furthermore, the flasher is not likely to fail in service as aresult of factors which normally would affect the sensitivity of such adevice.

A still further feature is that of continually working the bimetal whileit is hot. In the past considerabl trouble has been experienced inequalizing the on-time and off-time of bimetallic switches used inflashers. There is a tendency for the bimetal to take considerably moretime to straighten on cooling than to curl when heated. However, if thebimetal is maintained at a relatively high temperature where the heatdissipation is comparatively more rapid than it is at or near roomtemperature, a greater equality of the on and off periods results.

The above features and other advantages which will be apparent to thoseskilled in the art comblue to make the device particularly well suitedfor use in vehicle turn signal systems and adapted to mass production atlow cost; while in service it is highly dependable and emcient in itsoperation.

It is obvious that various changes may be made in the specificembodiment set forth for purposes of illustration without departing fromthe spirit of the invention. The invention is accordingly not to belimited to the specific embodiment shown and described, but only asindicated in the following claim.

The invention is hereby claimed as follows:

A flasher comprising a bimetallic strip fixed at one end thereof andfree at the other end thereof, a rigid member secured to the free end ofsaid strip and extending therebeyond, said strip being adapted to beheated in response to current flowing in a circuit and having anintermediate por- 6 tion of reduced width for rapid response to theinitiation and termination of current flow in said circuit, a resilientsheet metal switch blade anchored at one end thereof and free at theother end thereof, fixed members between which the free end of saidblade moves, one of said fixed members being provided with a switchcontact cooperating with the switch blade to make and. break saidcircuit, the fixed ends of said switch blade and said bimetallic stripbeing mounted in spaced relation and the switch. blade and bimetallicstrip extending in overlapping relation, said blade extending beyond theend of the bimetal strip and having an opening therein, an arched springpositioned in said opening and reckably connected at one end to theswitch blade and at the other end to the rigid member carried by thebimetallic strip, and a stop limiting movement of the bimetallic stripunder the influence of said spring when said strip is at ambienttemperatures, and the other of said fixed members between whichthe freeend of the blade moves limiting movement of the blade under theinfluence of the spring when the bimetal strip on heating operates theswitch blade through said spring to move it out of contact with thecontact carrying fixed member.

HENRY R. GROSS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

